Method of processing thermoplastic yarn

ABSTRACT

A METHOD OF HANDLING A PRE-BULKED YARN DURING A PROCESS INVOLVING HEAT TREATMENT IN A MANNER TO MAINTAIN UNIFORMITY OF BULK. THE PROCESS COMPRISES THE STEPS OF FORMING THE YARN INTO A LOOSE MASS, ENCLOSING THE YARN MASS WITHIN A FLEXIBLE BAG, HEATER TREATING THE YARN WHILE IT IS POSITIONED WITHIN THE BAG, AND FINALLY WITHDRAWING THE HEAT TREATED YARN FROMED THE BAG AND WINDING IT INTO A MORE CONDENSED PACKAGED FORM.

1971 T. L. GATES METHOD OF PROCESSING THERMOPLASTIC YARN Filed March 9, 1970 ATTORNEYS UnitedStatets Patent 3,619,875 METHOD OF PROCESSING THERMOPLASTIC YARN Terry Lee Gates, McAdenville, N.C., assignor to Pharr Yarns, Incorporated, McAdenville, N.C. Filed Mar. 9, 1970, Ser. No. 17,498 Int. Cl. B65h 55/04 U.S. CI. 2872 SP 8 Claims ABSTRACT OF THE DISCLOSURE A method of handling a pre-bulked yarn during a process involving heat treatment in a manner to maintain uniformity of bulk. The process comprises the steps of forming the yarn into a loose mass, enclosing the yarn mass within a flexible bag, heat treating the yarn while it is positioned within the bag, and finally withdrawing the heat treated yarn from the bag and winding it into a more condensed package form.

The present invention relates to the production of uniformly bulked yarns of thermoplastic synthetic fiber for use in various textiles such as carpets and pile fabrics. More particularly, the present invention relates to a method of handling a pre-bulked yarn mass during any heat treatment process in a manner which does not tend to destroy its previously developed bulk. In addition, the invention relates to a method of heat setting a pre-bulked yarn mass whereby the initial bulk will be retained during subsequent processing.

It is recognized that a portion of the bulk development of a pre-bulked or texturized thermoplastic yarn is lost when the yarn is subjected to undue tension, confinement, or handling during processing, particularly in those processes carried out at elevated temperatures. For example, bulked yarn is usually wound into package form for storage or shipment prior to heat setting and such packaging normally subjects the yarn to considerable tension and compression causing they yarn to lean out. To recover the lots or latent bulk, the yarn must again be treated, for example by exposure to steam, prior to heat setting. Otherwise, the latent bulk is lost and the yarn is re-set in its leaned out condition.

One presently employed method for reducing the tendency of bulked yarn to lean out during processing is to handle the yarn in skein form rather than wound package form. While the skein method of handling is generally effective to maintain uniformity of bulk and to permit the development of latent bulk, it is itself an inherently slow and therefore costly process. Additionally, the length of yarn in a skein suitable for handling (usually one pound) is relatively short thereby creating problems in piecing up the yarn for subsequent use. Piecing up is a particular problem in connection with carpet yarns for example, where the yarn cannot be tied with a knot, but rather, must be spliced in order to go through conventional carpet tufting machines.

The present method of handling bulked yarn finds particular application in a process for twist setting frieze or other hard twist type thermoplastic yarn. As used herein, the term frieze refers to a relatively highly twisted and plied unbalanced spun yarn having a tendency to curl upon itself and form loops or kinks. The conventional procedure for twist setting such yarn involves first removing the yarn from the twister package and placing it in skein form, relaxing the skeins to permit development of the desired kink by mechanically flexing the skeins in a tumble dryer or other similar rotary tumbling mechanism, heat setting the kink by subjecting the skeins to alternate cycles of vacuum and steam pressure in an auto- Patented Nov. 16, 1971 clave, opening and straightening the heat set skeins and placing them onto swifts, and finally backwinding the yarn from the swifts onto conventional bobbins.

In the above twist setting operation, it is not only important that the initial bulk be retained and be uniform, but also that a uniform kink distribution be obtained during relaxation of the skeins. Obviously, if there is a variation in either the bulk or the kink distribution in the yarn, unsightly streaks Will result in the finished fabric product.

It is accordingly an object of the present invention to provide a process for handling a thermoplastic yarn during a process involving heat treatment in a manner to maintain uniformity of bulk.

It is another object of the present invention to provide a process for producing a uniformly bulked and/ or kinked, permanently set yarn suitable for use in the fabrication of carpet and other pile fabrics.

It is a further object of the present invention to provide a process for producing heat set yarn which is significantly faster and more efficient than known production methods.

These and other objects and advantages of the present invention are achieved in the embodiment illustrated herein by the provision of a method for handling a thermoplastic yarn which comprises forming the yarn into a uniformly lightly confined or loose mass, enclosing the yarn within a flexible bag while maintaining its uniform and light confinement, heat treating the yarn while confined in the bag, and thereafter withdrawing the yarn from the bag and winding it onto a bobbin. In one embodiment, the yarn is a pre-bulked frieze type yarn and the process includes the steps of developing latent bulk and kink in the yarn prior to heat treatment by subjecting the yarn to a steam treatment and a tumbling action. The invention is applicable to a wide variety of thermoplastic yarns, such as nylon, polyester, or polyethylene.

Some of the objects and advantages of the invention having been stated, others will appear as the description proceeds when taken in connection with the accompanying drawings, in which FIG. 1 is a perspective view of a yarn collection can and a yarn conveying apparatus which may be utilized with the present invention;

FIG. 2 is a horizontal sectional view taken substantially along the line 2-2 of FIG. 1 and illustrating the placement of the yarn within the collection can;

FIG. 3 is a perspectiev view of a mechanism for inverting the can and transferring the yarn mass to a permeable FIG. 4 is a perspective view of the yarn package prior to relaxation of the yarns;

FIG. 5 is a perspective view, with parts broken away, of a rotary tumbling machine for use with the present invention;

FIG. 6 is a perspective view of the yarn package after relaxation of the yarns;

FIG. 7 is a perspective view of an autoclave which may be utilized with the present invention;

FIG. 8 is a fragmentary perspective view of a mechanism for withdrawing the yarn from the bag and winding it onto a bobbin.

Referring more specifically to the drawings, FIG. 1 shows a yarn processing station which includes a yarn collecting can 12, an associated supply bobbin 14 for the yarn 15, and a yarn conveying apparatus 16. Each can 12 is mounted on a circular base plate 18 which is rotatable about a vertical axis. The outer periphery of the plate 18 is in the form of a gear which is engaged by the mat-- ing pinion 20, and a motor 21 acts to drive the pinion 20 and thereby rotate the plate 18 and can 12.

The yarn conveying apparatus 16 includes a cylindrical tube 22 which is oscillated about the nOZZle 23 by the motor 24 acting through the crank 25 and link 26 such 3 that the lower end of the tube 22 traverses the can 12 generally radially in relation to its axis of rotation. The yarn from the bobbin 14 enters the upper end of the tube 22 and is drawn downwardly by a suitable air jet which is introduced into the tube 22 at the nozzle 23 via the conduit 28. The yarn 15 then exits from the lower end of the tube 22 and falls into the rotating can 12 to form a plurality of substantially evenly distributed radially directed loops or petals as illustrated in FIG. 2. If desired, steam may be introduced into the nozzle 23 with the air to aid in the development of the latent bulk in the yarn.

When the can 12 is substantially full, the outer periphery thereof is covered with an inverted bag which closely conforms to the outer periphery of the can. The bag 30 preferably is of a somewhat flexible and resilient construction and may, for example, comprise a nylon knit fabric which is permeable to both air and water vapor. The can is then itself inverted, either manually or by a suitable mechanism (not shown) and held aloft by an apparatus such as that illustrated at 32 in FIG. 3. Generally, the apparatus 32 comprises a pair of clamping arms 34 resiliently urged toward one another and which are adapted to engage the bottom edge of the can to retain it in its inverted position.

Once-the can 12 is inverted, the bag 30 (which is then upright) may he slipped down from the can and the yarn 12 will drop into the bag without significant disruption of its relative configuration. The bag is then tied off as shown in FIG. 4 to form a yarn package 35 wherein the yarn is retained in a substantially uniformly, lightly confined or loose mass.

To develop uniform kink in the case of frieze type yarn, the yarn package 35 is placed in a rotary tumbling machine 36 as shown in FIG. 5. The tumbler 36 is generally conventional and includes a revolving basket 38 having bafiles 39, and a driving motor 40. Typically, two packages 35 are placed in the tumbler and the speed. of the basket is such that the packages 35 are carried approximately to the top of the basket with the aid of the bafiies 39 before they drop to the bottom. As shown, the tumbler includes a steam inlet 42 and outlet 44 for aiding in the development of kink and latent bulk. In the case of balanced or straight yarn, it will be understood that the tumbling process may be eliminated.

After full development of the kink and bulk, the yarn will be somewhat expanded in volume, and the package will be longitudinally extended and circumferentially contracted to the configuration illustrated at 35 in FIG. 6. As noted above, the bag 30 is preferably somewhat resilient to permit such expansion of the yarn mass without exerting undue compressive forces which might tend to inhibit bulk and kink development.

To set bulk and kink (in the case of frieze type yarns) in the yarn, the packages 35' are positioned in a conventional steam autoclave unit 46 which is capable of being partially evacuated. Optimum conditions of vacuum, steam pressure and dwell times used in the heat setting process will naturally vary with the nature of the yarn being treated, the type of autoclave employed, and the yarn load. Generally, however, a vacuum is initially drawn to remove the air and thereby facilitate penetration of the steam into the innermost portions of the yarn. The subsequently introduced steam causes the yarn fibers to permanently assume the structural arrangement in which they are held in the yarn. A final vacuum serves to cool and set the yarn, and helps to remove the moisture of condensation.

While the heat treating process described above is particularly useful in conjunction with a heat setting process, it will be understood that the yarn package of the present invention is suitable for use in a wide variety of other treatment processes which involve the application of the heat, For example, in a yarn dyeing process, the package 35 may be used as a good yarn vehicle to prevent undue confinement of the yarn while being subjected to the heat treatment coincident with the dyeing process. I

From the autoclave 46, the packages 35' may be placed in a drying oven (not shown). The drying operation removes the remaining moisture of condensation which might otherwise cause the yarn to clean on during the subsequent backwinding operation.

The final operation involves opening the-packages 35, withdrawing the end of the yarn 15, and winding the strand onto a suitable bobbin 50. Surprisingly, the in: tegrity of the yarn mass will be maintained by the bag 30, and the strand may be rapidly removed without snarling.

It will be apparent to those skilled in theart that the above process permits a greater quantity of yarn to be handled than was possible with the previous skein method. It will be also apparent that since the yarn is retained in a substantially uniform and light confinement within the. bag, a uniform bulk is retained and development of a uniform kink during the tumbling process is facilitated.

Example I The following is a specific non-limiting example of a process for treating a thermoplastic yarn in accordance with the present invention. Two packages of a pro-bulked 2-ply 4.00-worsted spun nylon yarn, having 5 turns per inch of Z twist in the two ends or singles and 5% turns per inch of S twist in the ply, were conveyed through the yarn conveying apparatus 16 to a can 12 having a 12-inch diameter and height of 36 inches. Each yarn package weighed approximately 2 /2 pounds so that the can held approximately 5 poundsof yarn when filled.

Upon completion of the yarn feeding operation, the can 12 was covered by an inverted nylon knit bag which was approximately 12 inches in diameter and 42 inches in height. The can was then inverted and held aloft, causing the yarn mass to drop into the bag as the bag was lowered from the can. The open end of the bag was tied, producing a package having a diameter of about 12 inches and a length of about 26 inches.

The yarn package was next subjected to a steam-tumbling process to permit development of the latent bulk and kink. The steam was supplied to the tumbler at about 5 pounds per square inch (producing a temperature of about F. in the tumbler) and the rotary tumbling process continued for about 5 minutes. Two yarn packages were positioned in the tumbler during this process, and the packages grew in the length to about 32 inches and were reduced in diameter to about 9 inches.

A large number of similarly treated yarn filled packages were then positioned on the shelves of an autoclave of a type capable of being evacuated, and the autoclave was operated at a temperature of 270 F. to heat set the yarn. The yarn packages were then placed in a drying oven operated at a temperature of about F. for 5 hours, after which the yarn from each bag was fed onto a bobbin at a speed of-approximately 550' yards per minute.

' Example -II Two packages of apre-bulked 2-ply 3.40 worsted spun nylon yarn, having 4 /2 turns per inch of Z twist in the two ends or singles and 3 /2 turns per inch of S twist in the ply, were conveyed through the yarn conveying apparatus 16 and to the can 12 as described above. The. process was continued according to the previous example with the exception that the yarn package was subjected to steam without tumbling to develop latent bul-k prior to autoclaving;

In the'drawings and specification, there has been set forth a preferred embodiment of the invention, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.

I claim:

1. A method of handling and treating thermoplastic yarn to maintain uniformity of bulk in the yarn, said method comprising,

forming the yarn into a substantially uniformly loose mass,

enclosing the yarn mass within a flexible bag while substantially maintaining its condition of uniform looseness,

heat treating the yarn in its condition of uniform looseness by subjecting the yarn to a heat-setting temperature,

developing latent bulk in the yarn by subjecting the yarn to steam treatment prior to the heat setting of the yarn, and

withdrawing the heat treated yarn from the bag and winding the same into a more condensed package form.

2. The method as defined in claim 1, wherein the latent bulk in the yarn is developed by steam treatment as it is being formed into a substantially uniformly loose mass.

3. The method as defined in claim 1 wherein the flexible bag is vapor permeable and the enclosed yarn mass is subjected to steam treatment to develop the latent bulk.

4. The method as defined in claim 1 wherein the yarn is a frieze type yarn and which includes the step of developing kink in the yarn prior to heat setting by subjecting the enclosed yarn mass to a tumbling action.

5. The method as defined in claim 1 wherein the flexible bag is vapor permeable, the yarn is a frieze type yarn, and which includes the step of developing latent bulk and kink in the yarn prior to heat setting by subjecting the enclosed yarn mass to a tumbling action in a stern atmosphere.

6. A method of handling and treating a prebulked thermoplastic yarn to maintain uniformity of bulk comprising,

forming a package of the yarn by feeding the yarn into a container while rotating the container and traversing the yarn feeding point generally radially of the container relative to its axis of rotation whereby the yarn is laid up in a generally cylindrical package in loops which extend generally radially of the package, placing the package of yarn in a flexible bag to lightly confine the yarn while substantially maintaining the relative configuration of the yarn in the package,

heat treating the yarn while confined in the flexible bag by subjecting the yarn to a heat-setting temperature,

developing latent bulk in the yarn by subjecting the yarn to steam treatment prior to the heat setting of the yarn, and

withdrawing the yarn from the bag and winding it into a more condensed package form.

7. The method as defined in claim 6 wherein the yarn is a frieze type yarn and which includes the step of developing kink in the yarn prior to heat setting by subjecting the yarn to a tumbling action while it is confined in the fabric bag.

8. The method as defined in claim 6 wherein the bag is of a resilient knit fabric construction, the yarn is a frieze type yarn, and which includes the step of developing latent bulk and kink in the yarn prior to heat setting by subjecting the confined yarn to a tumbling action in a steam atmosphere.

References Cited UNITED STATES PATENTS 2,936,508 5/1960 Buddecke 2821 3,397,437 8/1968 McNeill et al. 2872 X SP 3,425,110 2/1969 Willis 2875 WT FOREIGN PATENTS 1,064,502 4/1967 Great Britain 2872 TCR LOUIS K. RIMRODT, Primary Examiner 

